Neurohormonal Profiles of Assistance Dogs Compared to Pet Dogs: What Is the Impact of Different Lifestyles?

Abstract

Assistance dogs must manage stress efficiently because they are involved in challenging tasks. Their welfare is currently a fundamental issue. This preliminary study aimed to compare assistance dogs (AD; n = 22) with pet dogs (PD; n = 24), using blood neuromodulator indicators to help find biomarkers that can improve the AD breeding, selection, training, and welfare monitoring. Both populations originated from different breeds, are of different ages, and had different lifestyles. Basal peripheral concentrations of prolactin (PRL), serotonin (5-HT), free (fOT) and total (tOT) oxytocin were measured by immunoassays. Multiple linear regressions were performed to assess the effect of activity, age, sex, and their interactions on these parameters. Correlations between neurohormonal levels were analyzed. No interactions were significant. fOT and tOT concentrations were significantly influenced by age (p < 0.0001 and p = 0.0002, respectively) and dogs' activity (p = 0.0006 and p = 0.0277, respectively). A tendency was observed for age effect on PRL (p = 0.0625) and 5-HT (p = 0.0548), as well as for sex effect on tOT (p = 0.0588). PRL concentrations were heterogenous among AD. fOT and tOT were significantly but weakly correlated (Pearson's r = 0.34; p = 0.04). Blood prolactin, serotonin, and oxytocin may represent biomarkers to assess workload and chronic stress-related responses in ADs and eventually improve their selection and training.

Keywords: Canis lupus familiaris; biomarker; free oxytocin; guide dogs; neuromodulator; prolactin; serotonin; stress; total oxytocin.

Figure 1

Linear regression models of T (Transformed) prolactin (a), T (transformed) serotonin (b), free oxytocin (fOT) (c), and total (tOT) (d) according to age, activity, and sex. Individual values are marked with points of different shapes and the regression lines are shown in solid or broken lines of different colors according to the legend. The parallel regression lines highlight that there is no interaction between the factors. Merged or closed regression lines indicate that there is no effect of the factors’ activity/sex, or not much difference between them, respectively. Identical slopes of the regression lines denote similar effects of the age, regardless of the dogs’ activity/sex.